Don't call suspend on DbgUiRemoteBreakin threads (#2281)

Sometimes it makes debuggee to hang.

Should fix #2244

pkg/proc/native/proc_windows.go

@@ -85,9 +85,11 @@ func initialize(dbp *nativeProcess) error {
 	// Suspend all threads so that the call to _ContinueDebugEvent will
 	// not resume the target.
 	for _, thread := range dbp.threads {
-		_, err := _SuspendThread(thread.os.hThread)
-		if err != nil {
-			return err
+		if !thread.os.dbgUiRemoteBreakIn {
+			_, err := _SuspendThread(thread.os.hThread)
+			if err != nil {
+				return err
+			}
 		}
 	}
 
@@ -195,7 +197,7 @@ func (dbp *nativeProcess) updateThreadList() error {
 	return nil
 }
 
-func (dbp *nativeProcess) addThread(hThread syscall.Handle, threadID int, attach, suspendNewThreads bool) (*nativeThread, error) {
+func (dbp *nativeProcess) addThread(hThread syscall.Handle, threadID int, attach, suspendNewThreads bool, dbgUiRemoteBreakIn bool) (*nativeThread, error) {
 	if thread, ok := dbp.threads[threadID]; ok {
 		return thread, nil
 	}
@@ -204,12 +206,13 @@ func (dbp *nativeProcess) addThread(hThread syscall.Handle, threadID int, attach
 		dbp: dbp,
 		os:  new(osSpecificDetails),
 	}
+	thread.os.dbgUiRemoteBreakIn = dbgUiRemoteBreakIn
 	thread.os.hThread = hThread
 	dbp.threads[threadID] = thread
 	if dbp.memthread == nil {
 		dbp.memthread = dbp.threads[threadID]
 	}
-	if suspendNewThreads {
+	if suspendNewThreads && !dbgUiRemoteBreakIn {
 		_, err := _SuspendThread(thread.os.hThread)
 		if err != nil {
 			return nil, err
@@ -261,14 +264,16 @@ func (dbp *nativeProcess) waitForDebugEvent(flags waitForDebugEventFlags) (threa
 			}
 			dbp.os.entryPoint = uint64(debugInfo.BaseOfImage)
 			dbp.os.hProcess = debugInfo.Process
-			_, err = dbp.addThread(debugInfo.Thread, int(debugEvent.ThreadId), false, flags&waitSuspendNewThreads != 0)
+			_, err = dbp.addThread(debugInfo.Thread, int(debugEvent.ThreadId), false,
+				flags&waitSuspendNewThreads != 0, debugInfo.StartAddress == dbgUiRemoteBreakin.Addr())
 			if err != nil {
 				return 0, 0, err
 			}
 			break
 		case _CREATE_THREAD_DEBUG_EVENT:
 			debugInfo := (*_CREATE_THREAD_DEBUG_INFO)(unionPtr)
-			_, err = dbp.addThread(debugInfo.Thread, int(debugEvent.ThreadId), false, flags&waitSuspendNewThreads != 0)
+			_, err = dbp.addThread(debugInfo.Thread, int(debugEvent.ThreadId), false,
+				flags&waitSuspendNewThreads != 0, debugInfo.StartAddress == dbgUiRemoteBreakin.Addr())
 			if err != nil {
 				return 0, 0, err
 			}
@@ -430,9 +435,11 @@ func (dbp *nativeProcess) stop(trapthread *nativeThread) (*nativeThread, error)
 	}
 
 	for _, thread := range dbp.threads {
-		_, err := _SuspendThread(thread.os.hThread)
-		if err != nil {
-			return nil, err
+		if !thread.os.dbgUiRemoteBreakIn {
+			_, err := _SuspendThread(thread.os.hThread)
+			if err != nil {
+				return nil, err
+			}
 		}
 	}
 

pkg/proc/native/threads_windows.go

@@ -16,7 +16,8 @@ type waitStatus sys.WaitStatus
 // osSpecificDetails holds information specific to the Windows
 // operating system / kernel.
 type osSpecificDetails struct {
-	hThread syscall.Handle
+	hThread            syscall.Handle
+	dbgUiRemoteBreakIn bool // whether thread is an auxiliary DbgUiRemoteBreakIn thread created by Windows
 }
 
 func (t *nativeThread) singleStep() error {
@@ -77,9 +78,11 @@ func (t *nativeThread) singleStep() error {
 	}
 
 	for i := 0; i < suspendcnt; i++ {
-		_, err = _SuspendThread(t.os.hThread)
-		if err != nil {
-			return err
+		if !t.os.dbgUiRemoteBreakIn {
+			_, err = _SuspendThread(t.os.hThread)
+			if err != nil {
+				return err
+			}
 		}
 	}
 

pkg/proc/native/zsyscall_windows.go

@@ -14,6 +14,7 @@ var (
 	modkernel32 = syscall.NewLazyDLL("kernel32.dll")
 
 	procNtQueryInformationThread   = modntdll.NewProc("NtQueryInformationThread")
+	dbgUiRemoteBreakin             = modntdll.NewProc("DbgUiRemoteBreakin")
 	procGetThreadContext           = modkernel32.NewProc("GetThreadContext")
 	procSetThreadContext           = modkernel32.NewProc("SetThreadContext")
 	procSuspendThread              = modkernel32.NewProc("SuspendThread")